Field of the Disclosure
The present disclosure relates generally to catalyst materials for reducing engine exhaust emissions, and more particularly, to improved close-coupled catalysts for three-way catalyst (TWC) applications.
Background Information
Current automotive catalysts largely depend on platinum group metals (PGM) (e.g., Platinum, Palladium, and Rhodium) in order to convert vehicle emissions to less noxious substances. However, the supply of said metals is limited even as automobile production increases as a larger portion of the world population adopts motorized vehicles for transport. Additionally, environmental concerns have led to ever more stringent NOX, hydrocarbon (HC), and particulate emission regulations being adopted in countries throughout the world. As such, there is a continuing need for catalysts able to provide better catalytic performance while maintaining reasonable use of PGM. One way of improving the light-off performance of a TWC close-coupled catalyst is to reduce its heat capacity per unit which can be accomplished by reducing the mass of the substrate by decreasing its wall thickness or increasing its porosity. Unfortunately, employing thinner or more porous walls can create a problematic reduction in the mechanical strength of the substrate.
Accordingly, there is a continuing need to provide TWC close-coupled catalysts capable of providing sufficient conversion so that stringent HC, NOX and particulates emission limits can be accomplished cost-effectively.